Golf balls are required to meet aerodynamic symmetry as prescribed in Professional Golfers' Association Rule, for example, the U.S. Golf Association Rule, Appendix III, Ball (C). It is required that when hit under given conditions, a ball has essentially no difference in trajectory and distance irrespective of different hitting positions.
In the conventional golf balls, dimples are distributed in symmetry with respect to a plurality of axes in order to accomplish aerodynamic symmetry. For instance, the phantom spherical surface of a golf ball is equally divided into planes of a regular hexahedral (6-sided), octahedral (8-sided), dodecahedral (12-sided) or icosahedral (20-sided) shape in which dimples are distributed. Among others, the regular icosahedral distribution wherein the ball surface is divided into equal 20 triangles of a regular icosahedron offers the maximum number of equally divided planes in equally dividing the spherical surface and has the maximum geometrical symmetry and the maximum number of symmetry axes, and is thus believed to provide improved aerodynamic symmetry. For this reason, various designs based on the regular icosahedral distribution have been proposed and implemented in practice.
Golf players have a consistent need for golf balls having improved flying performance. A variety of dimple arrangements have been proposed in order to improve flying performance, especially flying distance. Some golf balls whose dimple arrangement has improved flying performance, but less aerodynamic symmetry can be limited on use by the above-mentioned Rule. Therefore, the mainstream dimple arrangement is the regular icosahedral distribution.
However, other than the regular icosahedral distribution, regular octahedral and some other distributions are considered to provide dimple distributions having improved flying performance. There is a need for a regular octahedral or similar dimple distribution capable of meeting both the requirements of flying performance and aerodynamic symmetry.